I'm not sure if we're on the same family lines, but here's a stab at it. My Dad's name was Ervin, from a farm southwest of Battle Lake, MN. His father was Lawrence (Lorens) Enoch Thorstenson who was also born there. His father was Carl O. Thorstenson, who homesteaded there c.1869. Carl had a brother named Hans who came from Norway sometime after Carl and also farmed near Battle Lake.
Hans and Carl grew up on the Sundet Ostre Gard (farm) in Eidsvoll Kommune in northern Akershus fylke, a little north of Oslo. Their father's name was Torsten Hermandson and their mother's name was Else Mikkelsdatter.
Now, I remember my dad telling me that he had a cousin named Thore "back in Minnesota" (I grew up in Wisconsin) Might this be your father?
I have more info if it's helpful to any of you Thorstenson posters. Since my grandfather moved to Wisconsin in the 1930s, I don't have much information about the Minnesota branch of the family, and would appreciate learning more.